From patchwork Mon Jul 13 15:59:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Yongjun X-Patchwork-Id: 1328132 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=huawei.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4B57cv1k09z9sDX for ; Tue, 14 Jul 2020 01:59:27 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730215AbgGMP7Z (ORCPT ); Mon, 13 Jul 2020 11:59:25 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:34232 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729027AbgGMP7X (ORCPT ); Mon, 13 Jul 2020 11:59:23 -0400 Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 5DC39D54C4F417C8F8CB; Mon, 13 Jul 2020 23:56:14 +0800 (CST) Received: from localhost.localdomain.localdomain (10.175.113.25) by DGGEMS413-HUB.china.huawei.com (10.3.19.213) with Microsoft SMTP Server id 14.3.487.0; Mon, 13 Jul 2020 23:56:04 +0800 From: Wei Yongjun To: , Eric Dumazet , Taehee Yoo , Alexey Kuznetsov , "Hideaki YOSHIFUJI" , Jakub Kicinski CC: Wei Yongjun , Subject: [PATCH] ip6_gre: fix null-ptr-deref in ip6gre_init_net() Date: Mon, 13 Jul 2020 23:59:50 +0800 Message-ID: <20200713155950.71793-1-weiyongjun1@huawei.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-Originating-IP: [10.175.113.25] X-CFilter-Loop: Reflected Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org KASAN report null-ptr-deref error when register_netdev() failed: KASAN: null-ptr-deref in range [0x00000000000003c0-0x00000000000003c7] CPU: 2 PID: 422 Comm: ip Not tainted 5.8.0-rc4+ #12 Call Trace: ip6gre_init_net+0x4ab/0x580 ? ip6gre_tunnel_uninit+0x3f0/0x3f0 ops_init+0xa8/0x3c0 setup_net+0x2de/0x7e0 ? rcu_read_lock_bh_held+0xb0/0xb0 ? ops_init+0x3c0/0x3c0 ? kasan_unpoison_shadow+0x33/0x40 ? __kasan_kmalloc.constprop.0+0xc2/0xd0 copy_net_ns+0x27d/0x530 create_new_namespaces+0x382/0xa30 unshare_nsproxy_namespaces+0xa1/0x1d0 ksys_unshare+0x39c/0x780 ? walk_process_tree+0x2a0/0x2a0 ? trace_hardirqs_on+0x4a/0x1b0 ? _raw_spin_unlock_irq+0x1f/0x30 ? syscall_trace_enter+0x1a7/0x330 ? do_syscall_64+0x1c/0xa0 __x64_sys_unshare+0x2d/0x40 do_syscall_64+0x56/0xa0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 ip6gre_tunnel_uninit() has set 'ign->fb_tunnel_dev' to NULL, later access to ign->fb_tunnel_dev cause null-ptr-deref. Fix it by saving 'ign->fb_tunnel_dev' to local variable ndev. Fixes: dafabb6590cb ("ip6_gre: fix use-after-free in ip6gre_tunnel_lookup()") Reported-by: Hulk Robot Signed-off-by: Wei Yongjun Reviewed-by: Eric Dumazet diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 6532bde82b40..3a57fb9ce049 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -1562,17 +1562,18 @@ static void ip6gre_destroy_tunnels(struct net *net, struct list_head *head) static int __net_init ip6gre_init_net(struct net *net) { struct ip6gre_net *ign = net_generic(net, ip6gre_net_id); + struct net_device *ndev; int err; if (!net_has_fallback_tunnels(net)) return 0; - ign->fb_tunnel_dev = alloc_netdev(sizeof(struct ip6_tnl), "ip6gre0", - NET_NAME_UNKNOWN, - ip6gre_tunnel_setup); - if (!ign->fb_tunnel_dev) { + ndev = alloc_netdev(sizeof(struct ip6_tnl), "ip6gre0", + NET_NAME_UNKNOWN, ip6gre_tunnel_setup); + if (!ndev) { err = -ENOMEM; goto err_alloc_dev; } + ign->fb_tunnel_dev = ndev; dev_net_set(ign->fb_tunnel_dev, net); /* FB netdevice is special: we have one, and only one per netns. * Allowing to move it to another netns is clearly unsafe. @@ -1592,7 +1593,7 @@ static int __net_init ip6gre_init_net(struct net *net) return 0; err_reg_dev: - free_netdev(ign->fb_tunnel_dev); + free_netdev(ndev); err_alloc_dev: return err; }